Gold $20 Liberty Head Type 1 Double Eagle Hub Varieties
One of the more interesting aspects of the $20 Liberty Head Type 1 Double Eagle is that there were only two master hubs used for the entire series. The first master hub was used from 1850 until 1858. In 1859, a new master hub replaced the first and was used from 1859 until 1866.
What makes this interesting is that the first master hub actually had the word LIBERTY misspelled as LLBERTY. This was corrected by placing an I over the second L, but the original mistake can be clearly seen on those double eagles struck from 1850-1858.
Another way to see the change in master hubs is to look at the engraver's initials J.B.L. (i.e. James Barton Longacre) in the neck truncation on the obverse. On the original master hub, the initials can be seen directly below the hair curls. On the replacement hub, the initials have clearly been moved to the left away from the curls.
Although the misspelling of LIBERTY makes for an interesting error, it does not command a premium in the marketplace. This is because the error occurred on the master hub. The master hub was used to create a master die. The master die was then used to create working hubs which were used to create the working dies. It is the working dies from which coins are actually struck. Since the error occurred on the master hub, this error would have been transferred down to all the working dies, and therefore, can be seen on all Type 1 Double Eagles from 1850 through 1858.